1. Field of the Invention
The present invention relates to a substrate processing system and, more particularly, to the calibration and synchronization of components of the system.
2. Brief Description of Related Developments
Substrate processing equipment is typically capable of performing multiple operations on a substrate. U.S. Pat. No. 4,951,601 discloses a substrate processing apparatus with multiple processing chambers and a substrate transport apparatus. The substrate transport apparatus moves substrates among the processing chambers where different operations, such as sputtering, etching, coating, soaking, etc., are performed. Production processes used by semiconductor device manufacturers and material producers often require precise positioning of substrates in the substrate processing equipment. U.S. Pat. No. 5,931,626 discloses that a substrate transport robot may be taught the locations of the processing chambers and other components of the substrate processing system by providing the robot with the dimensions of the system and the components relative to the robot. One method of providing these dimensions is to manually move the end effectors of the robot to specific locations, record the movements, and “playback” the movements during processing operations.
However, this method of determining the locations of the system components is error prone. Measurement of the system dimensions and manual manipulations of the robot may be subject to human error. The precise location of system components may change slightly due to environmental changes, for example temperature and humidity fluctuations that may cause dimensional changes in parts of the system. In addition, seals, support structures, and other parts of the system may be subject to various types of stress, such as compression, and may change shape slightly over time in response. These factors, separately or in any combination, may affect the positioning of substrates within the substrate processing system.
It would be beneficial to provide a technique to correct for errors and changes in component locations, and to provide for more exact positioning of substrates in substrate processing equipment.